Segregated pressure fan



Oct. 17, 1939. w. H. BRETZLAFF ET AL 2,176,324

SEGREGATED PRES SURE FAN Filed Dec. 28, 1936 3 sheets-sheet 1 f f w/ w nm? m W n 56 A HP rs Z MW 1939- w. H. BRETZLAFF ET AL 2,175,324

SEGREGATED PRESSURE FAN Filed Dec. 28, 1956 3 Sheets-Sheet 2 INVENTOR.Vl a/ir firefy/a/f BY Czar/e6 P 6 /7/7765 ATTORNEY.

1939- w. H. BRETZLAFF ET AL 2,176,324

SEGREGATED PRESSURE FAN Filed Dec. 28, 1936 3 Sheets-Sheet 3 1 N VENTOR.w/f er MZ/eZy/aff ATTORNEY.

Patented Oct. 17, 1939 SEGREGATED PRESSURE FAN Walter H. Bretzlaif,Detroit, Mich., and Charles P. Grimes, Syracuse, N. Y.

Application December 28, 1936, Serial No. 117,748

3 Claims.

Our invention pertains to fans of improved 'efficiency and utility, andmore particularly to fans comprising means for segregating the air fromthe different pressure areas of the fan.

In previously known fans satisfactory operating efficiencies have notbeen obtained, and (Hillculty has been experienced because of thedifferent air pressures set up by the fan in adjacent areas whereby theenergy expended upon the air by the fan was largely dissipated inchurning the air and causing currents of air to flow in and out of thepath of the fan. More particularly such difiiculties have been veryserious when'projecting the air thru a conduit to a remote location fromthe fan, and previously when fans have. been utilized with conduits, 10weificiency and unsatisfactory operating characteristics have resulted.Also, it has previously been necessary to provide individual fans tosupply air separately to different locations for different pressure andvelocity conditions.

It is an object of our invention to provide a fan of improvedefficiency.

It is also an object of our invention to provide a fan comprising meansfor segregating the air projected from the different pressure areas ofthe fan whereby separated air streams may be supplied to separate pointsfor use under different pressure and velocity conditions.

It is also a further object of our invention to provide a segregatedpressure air source comprising a combination of an air impeller, and anair collecting plenum chamber, properly disposed in a high pressureportion of the air stream for receiving and segregating the airprojected from that portion of the impeller whereby it may be passedthrough an associated conduit for supplying air under higher pressure orhigher velocity conditions, and the 'air projected from the y otherportions of the fan may be utilized at a different location underdiiferent velocity and air conditions.

Another object of our invention is to provide a segregated pressure airsource comprising the 45 combination of a disk or propeller type fan, an.open sided pressure plenum chamber of annular conformation disposedadjacent the high velocity portions of the fan in the high pressure areaof the air stream, and a deflecting plate disposed at the side of theplenum chamber on the outer wall thereof for deflecting the projectedair into the pressure plenum chamber toward the axis of the fan, and forshutting off back eddies from the surrounding air.

1 A further object of our invention is to provide the combination of acentrifugal type of fan with a pressure plenum chamber of annularconformation surrounding the outer extremities of the fan and comprisingan open air receiving port extending around the inside portion of theplenum chamber and so disposed relative to the fan that the highpressure air is received therefrom and additional conduit meansinclosing the low pressure air therefrom in segregated relation.

The features that we consider characteristic of our invention are setforth particularly in the appended claims. The invention itself,however, both as to its organization and its method of operation,together with additional objects and advantages thereof will best beunderstood from the following description, when read in connection withthe accompanying drawings, in which:

Fig. l is a plan view of an embodiment of the improved unit, a portionbeing sectioned and broken away to more clearly illustrate theconstruction and arrangement of the unit and its associated elements;

Fig. 2 is a cross sectional view taken on line 22 thereof;

Fig. 3 is a view showing the pressure curve of a propeller type fandrawn to scale and associated with one of the propeller blades forillustrating the principle of operation of our invention;

Fig. 4 is a plan view partially sectioned and broken away showinganother embodiment of our invention as applied to a combined centrifugaltype and propeller type of fan;

Fig. 5 is a cross sectional view on line 5-5 thereof; and

Fig. 6 is an enlarged sectional view taken on line 66 of Fig. 4.

Referring more specifically to Figs. 1 and 2 of the drawings, we haveillustratively disclosed our invention comprising a segregated airpressure source. In this embodiment of our invention, the air deflectingfan comprises radially projecting blades 3 which are secured to a hubmember 5 which may be provided with a laterally projecting flange '1 onwhich the blades are secured in any suitable manner, as by rivet-s 9. Itwill be understood that the fan may be a propeller or disk type fan ofany well known construction. By disk type is meant any propeller fanwhether made of a unitary metallic disk or otherwise. The fan is mountedupon the extended shaft ll of a suitable motive means, such as anelectric motor l3, and it is rigidly secured thereon as by means of ascrew l5 for rotation clockwise as viewed in Fig. 1.

Disposed adjacent the high velocity sections of the blades 3 of the fanwe provide one or more plenum chambers of annular conformation. As willbe understood, we may use any portion, or portions, of these annuli asdesired, either for one outlet or for many separate outlets. For thispurpose we preferably construct a pressure plenum chamber or aircollector ring l7 comprising an outer annular side wall IQ of largediameter for surrounding in spaced relation an inner side wall 2| fordefining the plenum chamber space I! therebetween. The side walls i9 and2! of the plenum chamber are provided with a closed end portion 23 bywhich they are secured in spaced relation and the chamber is therebyclosed at one end.

For supporting the motor l3, three radially projected arms 25 areprovided in equal spaced relation, and they project inwardly from theinner wall M in inclined relation toward the common axis of theconcentric chamber walls.

The inner end of each arm 25 is provided with a curved finger 21 ofsuitable conformation for snugly gripping one end of the outer shell ofthe motor. The motor gripping fingers 2'! are preferably each covered bya rubber sleeve 29 whereby the motor is mounted in an insulatedcushioned relation in the axis of the pressure plenum chamber.

The other end of the fan motor is supported by means of a spider 3|which is provided with three arms 33 which extend radially therefrom forabutting the closed end 23 of the plenum chamber. A motor receivingsocket 35 is provided in the center of the spider for receiving theadjacent end of the motor shell, which may be cushioned snugly thereinby an annular cushion 31. For rigidly supporting the outer ends of thespider arms 33 in abutting engagement upon the closed wall 23 of theplenum chamber suitable spaced apertures 39 are provided therein andinternally threaded for receiving screws 4!. A suitable shim 43 ispreferably provided between the end of each spider arm 33 and the closedend of the pressure plenum chamber upon which the spider arm is snuglyclamped by means of the screw 4|.

The outer wall H! of the plenum chamber is elongated to completelysurround the outer extremities of the fan blades 3 in enclosingrelation. Upon the extended edge of the annular side wall I9 is provideda flange 45 for receiving the edge of an annular shell 41 which isdisposed snugly thereon and secured by screws 49 which are turned snuglyinto suitably threaded apertures provided in the flange.

The shell 41 encloses any open material or member through which the airis to be drawn and which provides a less than atmospheric pressure inthe entry plenum chamber, which is enclosed by the side Wall i9. Forthis purpose a filtering cartridge of any suitable construction may beinstalled in an inner side wall 5| with closures 53,'of disclikeconformation, of wire screen or other suitable open work constructionfor holding the filter material 55 in the filter cartridge whilepermitting the passage of air as it is drawn therethru by the fan intothe suction plenum chamber adjacent the intake side of the fan where apressure less than atmospheric is obtained.

Inaccordance with our invention we provide an annular deflecting plate56 which is secured in the open end or inlet of the plenum chamber IT.The deflecting plate 56 is disposed around the outer portion of the airreceivingport of the air collecting plenum chamber, and is of a suitablecurved conformation for enclosing the high velocity sections of the fanblades 3 as closely as possible in practical construction. The inwardlyextended portion of the deflecting plate 56 is provided with a reverselycurved edge 51. The space between the innermost edge of the defiectingplate and the inner wall 2| of the plenum chamber is made as narrow asit can be used and. take off the volume of air desired. The radiallocation of this annular opening, and the width thereof, can bedetermined from the test data plotted in Fig. 3, for this set up.

The annular deflecting plate 56 is so shaped and located as to guard thehigh velocity slip stream of the fan against interfering and deflectingcurrents that naturally tend to destroy the segregated high velocityareas that it is an object of our invention to preserve and utilize.

The annular deflecting plate 56 serves to defiect the high pressure airprojected fromthe fan and also to shut off the back eddies caused bynegative pressures which are induced by the outer extremities of the fanblades thus providing a segregated volume of high pressure air in theplenum chamber and greatly improving the desired operation of the fan.For leading the air from the air collector ring or plenum chamber H, aconduit 59 is provided in the outer side wall I9 where it connects froman outlet port 6|. The conduit 59 is secured to the outer wall l9 of theplenum chamber around the edges of the outlet 6| in any suitable manner,as by being welded for example, and it preferably extends tangentiallytherefrom. The outlet conduit is thus disposed in a proper direction forefficiently utilizing both the rotative velocity head and the pressurehead of the air which is thrown from the fan rotating clockwise, asshown in Fig. 1. The plenum chamber may also supply another outletconduit 60, of which any desired number may be provided. The conduit 59is made'of suitable cross section for connection with standard flues andconduits to carry the volume of air which is to be delivered undersuitable pressure and velocity conditions, in accordance with the usualventilating practice.

By this arrangement a single fan can be efiiciently utilized both fordelivering from the inner portions of the blade a large volume of lowpressure air, which is delivered in a broadly diverging stream and maybe utilized in the vicinity of, or directly in front of, the fan forexample, and for delivering a substantial volume of high pressure air,which is delivered thru the conduit 59 to be delivered in segregatedrelation for use under diiferent pressure and velocity conditions.

In operation, greatly improved eificiencies are obtained from oursegregated pressure fan and a single fan can be utilized for supplyingair under different pressure and velocity to different locations, thusobviating the necessity of providing a different fan for each difierentpurpose. The efficient delivery of air through a conduit, is alsorendered possible by means of our improved fan assembly.

The principle of operation of our segregated pressure fan will bereadily understood by reference to Fig. 3 of the drawings where an airvelocity curve is plotted in projected relation to a blade 6| of apropeller type fan. The abscissae of the curve are plotted to the samescale as the fan blade and represent the corresponding points adjacentthe fan blade where the velocity of the air stream was measured.

The measurements for plotting the ordinates of the curve shown wereobtained by means of an impact tube 63, which was connected through aflexible rubber tube 65 with a remotely disposed manometer tube 61, ofconventional construction, comprising a scale 69 of one leg forproviding visual manifestations corresponding to the pressures inducedin the impact tube 63 by the air stream from the fan. To obtain the datafor the curve shown, the end of the impact tube 63 was spaced one-halfinch from the plane of rotation of the propeller and moved along a lineparallel thereto as indicated.

Our data show a difierent curve for each range of spacings at intervalsof one-half inch further away from, or nearer to, the trailing edge ofthe blade. family of curves, best illustrated by the one-half inchseries here shown. Fig. 3 shows part of an interesting study of air flowthrough a fan mounted in an opening in wooden bafile 10, as shown. I

The attached graph shows t l 1 e values of velocity taken as a functionof \/h. The symbol h represents the height of the water column and thevalues of h were read from the manometer in inches of water. Thosevalues above the axis OA-BC-D are positive and indicate air was flowingtoward the impact tube as expected.

The values below the axis OA--B-C-D are negative and indicate air wasflowing away from p velocity in such close proximity, to the highestvelocity of out going air causing considerable interference therewithand entering the outlet side of the fan in the high velocity terminalportions of the blades.

Although the air velocity curves obtained from difierent fans variedsomewhat, that same difficulty was found in the operation of allproarated streams R airwhich may be separately I transmitted andutilized under different pressure and velocity conditions, at remotelyspaced locations, for which purpose any desired number of plenumchambers may be utilized.

By similar research on the centrifugal types of fans, we have discoveredthat similar adverse conditions also detrimentally affect. theiroperating characteristics and the efiicient operating principle of ourinvention may also be applied to fans of the radial or centrifugal type.It is also possible to provide our centrifugal type of segregatedpressure fan in a combined relation with a fan of propeller or disc typefor simultaneously delivering a large volume of low pressure air forapplication in the vicinity of the unit. The term air moving wheelwherever used designates a fan of either type. Such an embodiment. orour invention is illustratively disclosed in Figures 4, ,5 and 6 and isclaimed in our co- When plotted they make a pending patent applicationSerial No. 298,790 filed August '7, 1939.

Such a fan is conveniently constructed from a dished sheet metal member10, having cylindrical or conical side walls, and from which portions ofthe closed end wall are displaced to provide the radially extendedpropeller blades 13 which may be thereafter twisted to proper angularpositions and suitably curved. By suitably slitting the conical orcylindrical side Walls of the fan dish 19, blades H may be turned toprovide centrifugal or turbine blades, as will be readily understood. Acircumferential rim M is left uncut for connecting between the outerends of the propeller blades I3 and the lower ends of the turbine bladesH. The outer or open edge 11 of the sheet metal fan disc 10 arepreferably turned outwardly around a reinforcing rod 19 whereby a stiffreinforced rim is provided. At their innermost ends the propeller typeblades 13 are secured as by rivets 8| for rigid connection to flange 83upon a hub 85. The hub 85 is suitably apertured for axial mounting uponthe extended shaft 86 of a suitable motor 81 by which the fan is driven.

Surrounding and enclosing the centrifugal blades H of the cylindricalfan, we provide a scroll chamber 89 enclosed by walls 9| for re-'ceiving the air projected therefrom, and converting the velocity headthereof into a suitable in the direction of rotation at an angle ofdivergence which is preferably about 12 degrees, in accordance with theusual practice.

In practice we have found that fans of the centrifugal type also projectthe air into different pressure areas spaced axially along the outeredges of the fan blades, and in accordance with the principle of ourinvention, a pressure plenum chamber 93 is provided which is enclosed bysuitable spaced annular side walls 95, which pass through anintermediate portion of the scroll chamber. The side walls 95 are joinedby an external wall 9'! and the air collector chamber opens inwardlyadjacent the fan blades H.

The side walls 95 of the plenum chamber 93 are suitably spaced toprovide an open air receiving port adjacent the outer tips of the fanelements H, of a proper dimension for receiving and segregating thehigher pressure air therefrom. The outer peripheral wall 91 of theplenum chamber is also of angularly diverging conformation to define ascroll for receiving the high pressure air, which is thus converted froma velocity head to a pressure head. The inwardly directed edges of theplenum side walls 95 are tapered to provide sharp edged fins 96offeringminimum resistance to'the air stream. The scroll chambers 89 and93 may start from different circumferential points around the fan andmay be made with different angles of divergence as desired.

Connecting from the scroll chamber 89, a conduit 99 is provided whichleads tangentially therefrom for leading off the trapped air. As shownby Fig. 5, the cross section of the scroll chamber 89 is ofsubstantially elongated rectangular conformation at the point where theconduit 99 connects, but the conduit is preferably suitably tapered toprovide a proper cross section for connection with the standard conduitsgenerally used in accordance with the usual practice in the ill) in Fig.6, the chamber 93 is radially extended to the greatest extent at thepoint of connection into conduit llll.

For supporting the fan motor 81, bracket arms I03 extend in spaced apartrelation from the side Wall of the scroll chamber 89, and from each ofthe bracket arms I03 a motor supporting arm W5 projects radially towardthe axis of the fan. For supporting the shell of the motor, fingers it!of suitable curvature are provided on the inner ends of the arms I05.For holding the other end of the motor shell, it is nested in a socketill in a spider N19. The spider has a cushion bed M3 for the end of themotor and radially extending arms H4, which are secured by bolts I I5 tothe outer ends of the brackets 13. The fan is thus supported incushioned relation from the frame and housing of the air impelling unit.A flange Ill extends axially from the inlet end of the fan scroll St forreceiving a sleeve H9 which holds a shell EN. The shell I21 contains anyopen member or material l23 through which it is desired to draw the air.

In operation the blades E3 of the propeller fan draw air in through theshell 12! and discharge a large volume for use adjacent the fan unit.Simultaneously, the centrifugal fan is also drawing air through thefilter, and by a combination of fan forces, is throwing it through itsblades H in a generally radial and tangential direction across most'ofthe blade width.

By searching with the impact tube, .the various areas of segregatedpressures are found and recorded. The annular region of pressuresdesired is then housed over by a suitable scroll and may extend over acomplete circumference, or any portion desired, and for one or moretake-offs.

In this manner air is delivered by our fan unit for three difierentconditions of pressure and velocity. It will be readily understood thatthe principle of our invention may be applied and further extended byproviding additional plenum chambers, suitably segregated and connectingfrom the fan. In the various modifications, the fan blades termed aspropeller are either of curved sheet metal orof cast or forged air foilsection, as will be readily understood.

Aside from the specific embodiments of the invention here described, itwill be understood that numerous details of the construction may bealtered or omitted without departing from the scope of the invention asdisclosed and claimed, and that we do not desire to limit the inventionto the exact constructions herein set forth.

We claim:

1. In combination in a segregated pressure air impeller unit forsupplying high pressure air separated from a stream of air, a singleinlet chamber of suitable cross section for supplying air to the unit, adisk type of fan having air deflecting propeller blades extending fromits centerof rotation, means rotatably mounting said fan adjacent saidinlet chamber for moving a unidirectional air stream therethrough, andthe walls of said inlet chamber being of a suitable conformation forextending around the tips of said fan blades in closely enclosingrelation beyond the outlet side of the fan and the edges thereof beingturned in and back toward the fan to form an annular air collectingchamber to collect air from the high pressure portion of the air stream.

2. In combination in asegregated pressure air impeller unit forsupplying high pressure air separated from a stream of air, a singleinlet.

chamber for supplying air thereto, a rotatable disk type fan having airdeflecting propeller blades extending from its axis of rotation forprojecting a unidirectional air stream axially therethrough, an opensided air collecting plenum chamber of annular conformation disposed inthe highpressure portion of the air stream adjacent the high velocityportion of the plane of rotation of said blades and having its open sideadjacent thereto, and an annular air deflecting plate disposed in theopen side of said plenum chamber and curved around the blade tips towardthe outlet side fordeflecting air toward the inside of the chamber andshutting oil the currents of air which tend to enter the outlet side ofthe fan.

3. In combination in a segregated pressure air impeller unit forsupplying high pressure air separated from a stream of air, a singleinlet chamber for supplying air thereto, a rotatable disk type of fanhaving air deflecting propeller blades extending substantially radiallyfrom its axis of rotation for projecting an air stream axiallytherethrough, an open sided plenum chamber of annular conformationdisposed in the high pressure portion of the air stream adjacent thehigh velocity portion of the rotatable fan blades and having its openside opening toward the fan, said plenum chamber comprising an outerwall extended axially for closely surrounding and enclosing the outerextremities of the fan blades, an annular air deflecting plate disposedin the open side of the said plenum chamber for defleeting air towardthe inside of the chamber and shutting off the currents of air whichtend to enter the outlet side of the fan.

WALTER H. BRETZLAF'F.

CHARLES P. GRIMES.

